1. Field of the Invention
The present invention relates to the localized delivery of negatively charged therapeutic agents, and more particularly to the localized and controlled delivery of DNA absorbed to the surface of insertable medical devices, in particular, balloon catheters or stents.
2. Background of the Invention
It is often desirable to administer drug agents at localized sites within the body because the systemic administration of drug agents treats the body as a whole even though the disease to be treated may be localized. Various methods have been proposed for such localized drug administration. For example, U.S. Pat. No. 5,304,121, which is incorporated herein by reference, discloses a method of delivering water-soluble drugs to tissue at desired locations of a body lumen wall. The method generally includes the steps of impregnating a hydrogel polymer on a balloon catheter with an aqueous drug solution, inserting the catheter into a blood vessel to a desired location, and expanding the catheter balloon against the surrounding tissue to allow the release of the drug.
One potential drawback to conventional localized drug administration is the uncontrolled manner at which the drug or drug solution is released from the delivery device. It is often desired, if not necessary, to control and/or lengthen the time period over which the drug is released. For example, it might be advantageous to lengthen the release time from seconds to minutes, or from minutes to hours, days, or even weeks. Exceptionally long release times as long as several months are often desired, for example, where the drug is released from an implanted device such as a stent. Moreover, it is often desired to control the release rate of the drug over prolonged periods of time.
Gene therapy provides an alternative approach to combating many intractable cardiovascular diseases. A site-specific delivery of the genetic vectors to minimize systemic complications is crucial for the therapeutic potential of this approach to be realized. Advances in interventional radiology and innovative designs in balloon angioplasty and stents have raised that possibility.
The invention disclosed herein solves the potential drawbacks to the drug delivery methods and instruments of the prior art by providing novel apparatus and methods for the transfer of therapeutic agents, such as therapeutic genes, to internal body sites. The apparatus of the invention may be guided to diseased or deficient organs, or other lesions, and deliver the therapeutic agent in a targeted and controlled manner.